Friction control for cable drums



United States Patent [72] inventor Robert G.Ely

8321 Sanders Court, Fresno, California 93702 [21] Appl. No. 784,515 [22]Filed Nov.21, l968 n Continuation-impart of Ser. No. 684,749,

Nov. 21, 1969, abandoned. [45] Patented Nov. 3, 1970 [54] FRICTIONCONTROL FOR CABLE DRUMS 6 Claims, 9 Drawing Figs.

[52] U.S. Cl. 188/77, 188/259, 192/80 [51] Int. Cl. F16d 49/10 [50]Field ofSearch, 188/77, 26, 7 58, 259; 192/80 un Illllm References CitedUNITED STATES PATENTS 1,478,849 12/1923 Darnell 188/77 2,133,074 10/1938Bixby 188/77 2,249,282 7/1 941 Wellman 188/259 Primary Examiner-GeorgeE. Halvosa Attorney Huebner and Worrel Patented Nov.3, 1970 3,537,549

ROBERT 6. EL) INVENTOR Mal M Patented Nov. 3, 1970 3,537,549

Sheet 2 of 2 ROBERT 6. EL Y INVENTOR A TTORNYS FRICTION CONTROL FORCABLE DRUMS CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of applicants copending U.S. Pat. application Ser.No. 684,749, filed Nov. 21, 1967, now abandoned. for Improved FrictionControl For Cable Drums".

BACKGROUND OF THE INVENTION The present invention relates to a brakingdevice for a cable drum and more particularly to an improved frictioncontrol device for controlling the rotation of a cable drum or any otherrotary member in a smooth, gradual and precise manner.

Heretofore, cable drums have been equipped with brake devices whichconsist-essentially of a brake drum, a brake band in circumscribingrelation thereto and a brake lining supported by the brake band adaptedto be brought into braking engagement with the brakedrum by constrictingthe brake band. In the operation of cranes it is highly desirable tocontrol the cable drums precisely in the raising and lowering of itemsin order that they be delivered to the point of delivery in a safe andreliable manner. However, such desired precision of control has not beenuniformly attained for the reason that it is extremely difficult toconstrict the brake band with such precision. More often than not, thecable drums revolve rapidly or are grabbed and completely stopped.Furthermore, the transition from rapidrotation to a complete stop occursin such a brief period of time that severe shock loads are imposed uponthe lifting cables with the attendant danger of snapping the cables,thus requiring the use of oversized cables to provide a sufficientfactor of safety.

SUMMARY OFTHE INVENTION It is therefore an object of the presentinvention to provide an improved friction control device for controllingthe rotation ofa rotary member'in a smooth and gradual manner.

Another object is to provide a braking device for cable drums and thelike for achieving graduated control of the rotation thereof.

Another object is to provide a braking device substantially uniformlyoperable in a manner to apply smoothly varying degrees of brakingaction.

Another object is to provide an auxiliary brake pad in conjunction witha brake lining, which pad is engageable with a brake drum prior toengagement of the lining therewith.

Another object is to provide a braking device of relatively inexpensiveconstruction for control ofthe rotation ofa rotary member, which deviceoperates in a rapid reliable and facile manner to achieve such control.

These and other objects and advantages are achieved by a braking deviceconsisting essentially of a brake drum, a brake band in circumscribingrelation to the brake drum which supports a brake lining in operativerelation to the brake drum, and a friction pad adjustably mounted on thebrake band. In one form, the brake band and the brake lining aresegmented, the segments ofthe brake band being interconnected by aplurality of bridging brackets, each having a rectangular recessslidably receiving a rectangular plate adjustably supported in therecess by a member having one end thereof journaled in the plate and anintermediate portion thereof threadedly engaging the bracket, the platehaving secured thereto a pad of resilient material to which a pad offriction material is affixed. In another form of the device, theadjusting mechanism includes a spring for resiliently holding the platein adjusted position to avoid or minimize overadjustment. Still anotherform of the device provides an auxiliary friction pad attached to aconventional braking system having a brake band, the pad being mountedfor adjustment on the brake band. Thus, by adjustment of the supportingplate, the friction pad can be positioned in closer adjacency to thebrake drum than the remainder of the brake lining, initial constrictionof the brake band serving first to bring the friction pad into brakingcontact with the brake drum, continued constriction resulting inincreasing the degree of bi'aking action, culminating with theengagement of the brake lining to effect a complete stoppage of therotation of the brake drum.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an elevational view of one formofa braking device embodying the principles of the present invention.

FIG. 2 is a fragmentary sectional view of the device on a larger scale.

FIG. 3 is a plan view ofthe structure of FIG. 2.

FIG. 4 is a vertical sectional view taken generally on line 44 of FIG.2.

FIG. 5 isa fragmentary elevational view of a modified form of thedevice.

FIG. 6 is an enlarged transverse section of the device of FIG. 5.

FIG. 7 is a fragmentary elevational view of a conventional brakingarrangement having a brake band and illustrating the manner ofadjustably mounting a friction pad attachment thereon.

FIG. 8 is an enlarged elevational view ofthe friction pad attachmentofFIG. 7.

FIG. 9 is an enlarged sectional view taken on line 9-9 of FIG. 8.

DETAILED DESCRIPTION OF THE EMBODIMENTS First Form Referring to FIG. 1,there is illustrated an improved friction control device 10 embodyingthe principles of the present invention and consisting essentially of abrake drum I2, and a brake band 14 which supports a brake lining 16 inoperative relation to the brake drum. The brake drum I2 is fixed to anaxle or shaft 18 suitably journaled for rotation in a support standardor bracket 20 and is suitable secured to a cable drum, not shown,whereby the braking action of the device I0 serves to controltherotation of the cable drum. Brake band 14 and brake lining 16 aredisposed in circumscribing relation to the brake drum I2, braking actionbeing effected by constriction of the brake band by conventional linkagedesignated generally by a reference numeral 22 and operating in awellknown manner. The described structure is conventional and familiarto those who operate machines employing cable drums. V I

The friction control or braking device 10 of the present invention isstructurally featured by segmenting the brake band and the brake lining,adjacent ends of the brake band segments being interconnected bybridging brackets 24. Viewing FIGS. 2 and 4, it will be noted that theadjacent ends of the segments of the brake band 14 are spaced apart, thespacing therebetween being bridged by the bridging bracket 24 whichincludes an arch-like U-shaped member 26, the legs of which are joinedto the segments ofthe brake band 14, such juncture being strengthened bymeans of arcuate plates or gussets 28. The member 26 is formed toprovide a generally rectangular recess 30 in the interior thereof inwhich a rectangular plate 32 is rdjustably supported for radial slidingmovement by means of an adjusting screw 34 having one end thereof 1rotatal ly connected to the plate 32, as at 36, the other end thereofbeing provided with a finger knob 38. The intermediate portion ofthescrew 34 is thrt-adedly connected to the member 26 and to a nut 40 forlocking the screw to the 3 the segments of the brake band 14. The gapsbetween adjacent ends of the segments of brake lining 16 are closed ineach instance by a friction pad 48 having substantiallythe samecurvature as the brake lining and providing therewith a substantiallycontinuous braking surface when in alignment therewith. The pad 48possesses substantially the same rectangular dimensions as plate 32 andpad 46 and is suitably secured to the latter as by adhesion. bonding orthe like.

The material of the friction pad can be similar to that ofthe brakelining. Preferably. however, the pad #58 is made of hemp or the like toprovide sufficient friction for the purpose and in addition to clean andslightly lubricate the brake drum. thereby prolonging the life of thefriction pad and the drum.

Adjusting screw 34 can be turned to adjust the position of the frictionpad 48 in closer adjacency to the brake drum 12 than the brake lining16. Such positioning of the friction pad provides that, upon initialconstriction of the brake band M, the pad is the first portion offriction material that is brought into braking engagement with the brakedrum, further constriction bringing the braking face ofthe pad intotighter braking engagement and thereby increasing the degree of brakingaction. The compressibility of the pad 46 aids in increasing the degreeof braking action while permitting movement of the pad 48 into alignmentwith the brake lining l6. whereupon a full braking action is attained.Graduated control of the brake drum l2 and the cable drum to which it issecured is thus achieved for a smooth, gradual and precise control oftherotation of the cable drum. Release of the drum for rapid rotation isalso accomplished in a smooth and gradual manner by reversing theprocedure first to take the brake lining 16 out of engagement with thebrake drum I2 and, lastly, the pad 48. after the degree of its brakingaction is gradually reduced by the action of the pad 46 in expandingfrom its compressed condition.

it will be appreciated that the several pads 48 can he differentlypositioned with respect to the brake drum 12 in order that the brakingaction from initial to final constriction ofthe brake band can be madein small increments and that additiorial bridging brackets and frictionpads can be provided to diminish the size of each increment and providefor a greater range of graduated control.

OPERATION OF FIRST FORM The operation of the first form of the device ofthe present invention is believed to be clearly apparent and is brieflysummarized at this point. With the adjusting screws 34 adjusted toposition the pads 48 associated therewith as desired to provide thedegree and graduation of control preferred, the cable drum and the brakedrum are connected to a source of power and rotated to perform an itemhandling operation. As the item nears its destination or pointofdelivery, the linkage 22 is initially actuated to constrict the brakeband 14 slightly, which places the pad 48 that is in closest adjacencyto the brake drum 12 in braking engagement therewith, thereby exertinga, small degree of braking action. Further constriction of the brakeband 14 brings the other pad or pads 48 into effective engagement withthe brake drum 12 in accordance with their distance therefrom. therebybringing into play additional sur faces of braking material andincreasing the degree of braking action accordingly. Full constrictionof the brake band 14 serves to bring the brake lining 16 into contactwith the brake drum 12 with such pressure as to brake the drum and itsassociated cable drum to a full stop. In lowering an item, the linkage22 is actuated for first releasing the brake band 14 for disengagementof the brake lining l6 and as many of the pads 48 as necessary to havethe cable unwind from the cable drum at a desired speed. the disengagedpads and brake lining i6 being reapplied gradually as the item reachesits point of delivery.

, Second Form Referring to FIG. 5, there is shown a modified form ofafriction control device l0 embodying the principles of the presentinvention which is quite similar to the device It) previously described.Accordingly, corresponding parts are designated by corresponding primenumerals. The device 10 consists essentially of a brake drum lZ'and abrake band 14' which supports a brake lining l6'in operative reiation tothe brake drum. It will be appreciated. of course. that the brake drumis circular and is circumscribed by the lining and the brake hand whichis suitably supported in operative relation to the brake drum asdescribed in greater detail in connection with the first form of thedevice.

The brake lining and the brake band are segmented. the ad jacent ends ofthe brake band segments being interconnected by a bridging bracket24'which includes an inverted U-shape d channel member 26'. Secured tothe member 26'is a pair of parallel plates or gussets 28'of generallytrapezoidal shape having lower arcuate edges suitably configured to thecurvature of the brake band l4and secured thereto. The upper portions ofthe gussets are interconnected by a plate 50 disposed atop the channelmember 26..The plate 50 is perforated to provide an aperture 52.Coaxially aligned with the aperture 52 is a perforation 54 formed in thetop of the channel member 26which is of greater size than the aperture.Disposedin the perforation 54 is one end ofa guide sleeve 56 having anouter diameter snugly fitted therein and an inner diameter equal to thatof the aperture and aligned therewith, as shown in FIG. 6. 1

Passing freely through the aligned aperture and sleeve is a rod 58. theupper portion of which is threaded, and to the lower end of which isfixed a rectangular supporting plate (it) fitted for sliding movementwithin the channel menibcr ZtS'. 'ihrcadediy engaged with the upperportion of the rod 58 is a finger knob 62 for adjusting the position ofthe plate 60. Surrounding the sleeve 5'6 is a compression spring 64which reacts between the channel member and the support late for biasingthe plate toward'the brake drum and resiliently holding the plate inadjusted position.

Suitably secured to the underside of the plate 60. as by adhesion,bonding or the like, is a rectangular friction pad 48' substantiallysimilarly dimensioned as the plate and of material similar to that offriction pad 43.

The friction pad 48is disposed in the gap between adjacent ends of thesegments of the brake lining l6and is adjustable relativcthereto. Suchpositioning of the pad 48provides that, on initial constriction of thebrake hand l4, the pad is the first portion of friction material that isbrought into braking engag'ement with the brake drum 12, furtherconstriction bringing the pad into tighter braking engagement andthereby increasing the amount of braking action for gradually slowingdown the rotation of the brake drum and parts connected thereto. Thecompressibility of the spring 64 aids in increasing the braking actionslightly while permitting movement of the pad into alignment with thebrake lining lfi'whereupon a full braking action and complete stoppageof the drum is attained. The compressibility of the spring also permitsinward movement of the pad during the braking action into alignment withthe brake lining for minimizing undue wear on the pad because of anyovcrndjustmcnt thereof.

OPERATION OF SECOND FORM The operation of the second form of the deviceis briefly summarized. With the finger knob 62 adjusted to position thefriction pad 48relative to the brake lining l6as desired to provide thedegree of graduation of control preferred, the brake drum is connectedto a source of power and rotated to perform an item handling operation.As the item nears its destination or point ofdclivery. the brake handMis initially constricted which places the friction pad 4flin brakingcngagcment with the drum 12, thereby exerting a small degree of brakingaction. Further constriction of the brake band a brings the pad intotighter engagement with the drum, thereby increasing the degree ofbraking action accordingly. Full constriction of the brake band servesto bring the brake lining into Third Form Referring to FlG. 7, there isshown a third form of the improved friction control device of thepresent invention v 22' which includes a swinging arm 22a and a pivot22p. As will be appreciated from viewing FIG. 7, clockwise swinging ofthe arm 22a causes the brake lining to be disengaged and spaced from thebrake drum, reverse movement of the arm serving to engage the liningwith the drum.

' Inviting attention also to FIG. 8, the attachment 10a includes asupporting plate 70 connected at one end thereof for pivotal movementrelative to the brake band by means of a pivot pin 72 and abracket 74fixed to the brake band 14'. A friction pad 48" is suitably secured tothe plate 70 as by adhe' sion, bonding or the like. The pad 48" can bemade of any suitable material but is preferably made of hemp or the likefor reasons stated in connection with the friction pad' 48. The plate 70and the pad 48" can be arcuately configured to provide for engagingthepad effectively with the brake drum when the attachment is moved towardthe brake drum on appropriate actuation of the arm 22a toswing the otherend of the brake ba-nd inwardly about the pivot 22p.

To achieve abraking action by the pad 48" ahead of the brake lining l6",provision is made for adjustment of the pad .to place it slightlyradially inwardly of the brake lining. For

this purpose, the support plate70 has fixed thereto a bracket 76. Asshown in FIG. 9, the bracket 76 has a noncircular perforation 78 whichis in substantial alignment with a guide sleeve 80 secured to the brakeband 14". Passing through the sleeve 80 and the perforation 78 is a rod82 having a head 84, a noncircular shank portion 86 adjacent to the headand a distal threaded end 88. Disposed about the sleeve 80 and reactingbetween the bracket 70 and the brake band 14" is a compression spring90. Threadedly engaged with the threaded end of the rod is a finger knob92, the rotation of which adjusts the position of the pad 48". Thespring serves to hold the pad 48" resiliently in such adjusted positionfor minimizing wear of the pad resulting from any overadjustmentthereof. The perforation 78 is slightly oversize to permit articulationof the plate 70 relative to the rod 82 while preventing rotation of thelatter.

OPERATION OF THIRD FORM invention is likewise believed to be apparent.With the pad 48" adjusted to provide for desired advance engagementthereof ahead of the brake lining 16", actuation of the linkage 22' tocause inward swinging of the brake band about the pivot 22p firstengages thepad to achieve a small degree of braking action. Furtherconstriction of the braking band brings the brake lining gradually intoeffective engagement with the brake drum for gradual controlled stoppingthereof. Reverse actuation of the linkage provides for obtaining thesame gradual effect in the opposite direction.

. There have thus been provided different forms of an improved frictioncontrol or braking device of inexpensive construction by which graduatedcontrol of the rotation of the cable drum or other rotary member can beachieved in a smooth, rapid, reliable and facile manner.

Although the invention has been herein shown and described in what areconceived to he the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention.

lclaim:

1. Means for braking the rotation of a rotary member com prising a brakeband, a brake lining of arcuate curvature supported on the band formovement relative to the member, said lining being in sections, saidbrake band having mounted thereon a bridging bracket with substantiallyrectangular dimensions, a generally rectangular plate adjustablyslidably supported within-the bracket, one of said sections havingsubstantially the same dimensions as the plate and being secured theretofor movement therewith for selective adjustment and placing said onesection out of arcuate alignment with the remainder of the lining.

,2. The braking means of claim 1 in which said one section is secured tothe plate by a pad of compressible material.

3. A friction control device comprising a brake drum mounted forrotation; a brake band mounted in operative relation to the drum; abrake lining secured to the band providing spaced segments disposedabout the drum, said band being adapted to be constricted to effectengagement of the lining 1 with the drum for controlling the rotation ofthe drum; a pad of friction material mounted on the band in inwardlyspaced relation to said lining to provide a braking surfaceengageablewith the drum prior to engagement of the lining therewith incident tosaid constriction of the band; resilient means biasing said pad towardthe drum but permitting retraction of the pad into alignment with thelining upon engagement of the lining with the drum, said brake bandincluding a pair of sections having a gap therebetween; a bracketinterconnecting the sections and bridging the gap; and a support platemounting said pad on the bracket for movement within the gap along anaxis extending substantially radially of the band and lining.

4. The device of claim 3 in-which the support plate has connectedthereto a rotatable member screw-threadedly engaging the bracket forselective adjustment of the plate and pad.

5. The device of claim 3 in which the support plate has secured theretoa nonrotatable screw-threaded member, means biasing the plate toward thedrum, and means engaging the screw-threaded member and bracket formoving the plate against the bias of the biasing means.

6'. The device of claim 5 in which the screw-threaded member is a rod,and the biasing means is a compression spring surrounding the rod andreacting between the bracket and the plate.

